Current commercial decaffeination of coffee is effected by the removal of caffeine from whole, green coffee beans. The beans are moistened and then extracted with a solvent which is relatively specific for caffeine. The solvents employed commercially are either a chlorinated hydrocarbon solvent, such as discussed in U.S. Pat. No. 3,671,263 to Patel et al. or a caffeine-deficient water solution of coffee solubles, such as disclosed in U.S. Pat. No. 2,309,092 to Berry et al. both of which are herein incorporated by reference.
In the decaffeination process of U.S. Pat. No. 2,309,092, which is commonly referred to as the water extraction system (Note: Sivetz, Coffee Processing Technology, Vol. 2, p. 208, AVI Publishing Co., Inc., 1963), the caffeine laden water extract, resulting from contact between caffeinecontaining green coffee and the caffeine-deficient water solution, is solvent extracted in order to remove caffeine. Typically these solvents are the same chlorinated hydrocarbons which are employed in the direct solvent extraction processes, exemplified by the aforementioned 3,671,263 patent.
As a result of the presence of organic solvents, such as chlorinated hydrocarbons, in commercial green bean decaffeination processes, the decaffeinated coffee products presently being sold, either roasted and ground or soluble, contain at least trace amounts of residual solvent. Since presence of chlorinated, or other halogenated compounds in food products is becoming the subject of increased governmental regulation, it would be desirable to identify and employ a non-halogenated solvent for the decafeination of coffee.
The main feature of any system of decaffeinating coffee, such as in the decaffeination of whole green coffee beans, is to identify a non-toxic solvent in which caffeine is readily soluble and in which non-caffeine coffee solids are insoluble or poorly soluble and which solvent can be removed from the coffee without deteriorating or materially changing the chemical composition of the bean.